1. Field of the Invention
This invention relates generally to injection molding. In particular, this invention relates to nozzles for conveying plasticized material to cavities within a mold assembly.
2. Description of Related Art
It is known to provide nozzles to convey material in a flowable condition from, for example, a melt distribution manifold to cavities of a mold assembly wherein a nozzle tip is removably connected with a nozzle assembly and comprises a tip outlet that is in fluid communication with an inlet, a so called “gate”, of a mold cavity. It is also known to provide nozzles comprising valve pin members effective to be selectably seated to prevent flow from the nozzle body into a mold cavity. Known constructions of nozzle assemblies comprising removable nozzle tip members are susceptible of misalignment between the nozzle body and nozzle tip that cause misalignment of the nozzle tip relative to a mold block. For example, tilt of the nozzle tip relative to the longitudinal axis of the nozzle body can occur. Further, known constructions of nozzle assemblies comprising valve pin members are susceptible of misalignment between the pin member and the nozzle and/or mold component with which the pin member is to seat, i.e., the valve seat of the nozzle tip or the mold assembly.
Constructions to overcome misalignment of the nozzle body and removable nozzle tip are known wherein an alignment bearing is provided on the nozzle tip and an alignment surface is provided on the nozzle body such that contact of the alignment bearing with the alignment surface is effective to prevent tilt and achieve concentricity of the nozzle tip relative to the longitudinal axis of the nozzle body. In such known constructions, a guide structure for guiding a valve pin member to effect desired alignment of the valve pin tip end and valve seat may comprise elements in tandem with the nozzle tip or at the gate. Because tandem guide members are not aligned by the alignment bearing of the nozzle tip, misalignment, for example, tilt of the guide member relative to the longitudinal axis of the nozzle body, may arise between the guide member and nozzle tip that may result in increased wear of the guide member, valve pin member and valve pin seat.